The mystery girl
by Astraea91
Summary: Alexis was a normal girl with a normal family. When tragedy strikes she finds herself thrown in to an unknown world of angels and demons, of heros and monsters. She doesn't know who to trust and must find out her true identity to survive in this new world. Includes characters from the Mortal Instruments.
1. chapter 1

**Chapter** One

 _The neat square hole in the ground looked bottomless, devouring all light that entered in to the void. Thin skeletal hands creeped out over the edge and blindly felt their way along the wet grass, twitching and groping for anything in their path. The rain drizzled down and coated their grey skin in a shine._

Alexis blinked and glanced around, her bloodshot eyes darting between the pale faces in the crowd gathered around her. She had been staring unblinking at the scene before her without realising. Turning her gaze back to the hole in the ground the vision was suddenly gone, only to lay bare her own horror before her; two coffins slowly being lowered in to their grave, side by side. Together.

As in life, so in death.

The funeral passed in a grey discoloured haze, and Alexis stumbled through it, accepting hugs and condolences, playing the part of a grieving daughter. Her mind just felt numb though. Was she supposed to be a crying wreck? Screaming for her parents and the injustice that has been dealt to her? No one tells you how you're supposed to act.

"Alex, can you come here a sec?"

She looked up from the plate of half-eaten food she had been nibbling at and gave a weak smile. Standing up she placed the plate aside and followed her crew mate out in to the hallway. Leaning one shoulder against the wall she crossed her arms and sighed in relief at the quiet. The constant chatter in the living room had felt like wasps swarming around her mind.

Her crew mate, Jake, looked down at her in concern.

"You don't have to be here, you know," he murmured as he nodded towards the room behind her.

"Yes, I do," Alexis replied, giving him a stern look. "I'm their only child, and I'm an adult now. I'm expected to do all of this."

Jake pursed his lips and shook his head. "You don't need to torture yourself over this. You can't change the -"

"My parents were murdered, Jake. And the investigation team say they don't have any leads? Bullshit. They're either lying to me or can't do their job. I'm going to find answers even if I have to do it all myself. But, for today, I have to host this damn wake."

Alexis spun on her heels to go back in the room when Jake grabbed her arm. "Just don't burn yourself out, okay? I need my partner in crime back at work. They've put me with Derek and he's driving me nuts. Let me know if you need anything."

A smirk had started to rise on her lips at that. Derek was so old and boring it's a wonder Jake hadn't crashed the ambulance just to get out of it.

"I'll let you know. Thanks, Jake." With that she disappeared back in to her parent's living room and left her friend standing there, looking a little lost without her.

Alexis and Jake had been work partners for about a year now. He was a few years older and was her mentor in the ambulance service, forever teaching her on the job and keeping her entertained. He was sweet and helpful, and had helped to bring her out of her shell. Shyness was a weakness that She hated. She guessed he could probably do with a break from her, in all honesty.

Slipping unnoticed in to the room she began tidying up the empty plates and glasses, engaging in the standard boring conversations with family members she hasn't seen in years. _How grown up you look Alexis! How's work? You do such a brave job. How interesting. Are you married with kids yet? No, why heavens not?! A catch like you! I'm so sorry to hear about your parents, terrible, terrible... is there any dessert?_

She kicked everyone out by the time the sun had gone down, waving goodbye to old great aunt Maureen as she hobbled to her car. Finally shutting the door she leaned against it and closed her eyes, took ten deep breathes, then slowly opened them. The house was covered in darkness and the stillness soothed her.

Deciding that a bath was in order Alexis jogged up to the bathroom and turned the taps on. The steam quickly filled the small room and felt like a sauna, cleansing the grimey feeling that had been building up all day. Slipping in to the bath she immersed herself beneath the bubbles, and although she felt her muscles relax her mind was still whirring. It never seemed to stop.

The death of her parents weren't right, it wasn't natural... Something had killed them, but what? Nothing made sense.

Just then a creeping cold had begun to seep in to her bath water and she straightened up. Looking down at her legs the water was turning an opaque black, and all of a sudden a dark withered hand burst out of the water and grabbed her leg. She could feel the jagged nails tearing in to her skin! Gasping with shock she drew her legs back and was about to clamber out of the tub when the hallucination reverted and all she saw were the bath bubbles, upset by the ripples in the water.

Hallucinations. That's what these had to be. Brought on by the stress of her parents dying, surely. That made the most sense. Yet they felt so real... and something was holding her back from telling anyone about it. Running a hand down her leg she searched for any kind of proof that it wasn't real. Only... those scratches were new. Lifting her leg up she saw the 3 jagged bloody lines down her shin and dropped the leg back in the water.

What the hell is happening?


	2. Chapter 2

**Chapter 2**

The pounding on the door startled Alexis awake and she looked around blindly for the clock on her beside table. 8:12am.

Flinging the covers back she groaned as she pushed herself out of bed and hobbled down the hall to the front door; her limbs were stiff and aching from the sleep.

"Alright, jeez. Where's the fire?" She muttered and snorted at herself.

Unlocking the door she opened it a crack before pulling it wide a moment later, a look of surprise on her face. "Jake? Do you realise how early it is?"

Jake smiled wide and lifted up a brown paper bag. "Just finished a night shift. I brought your favourite breakfast – sausage and egg baguette with brown sauce and... a tea."

Mocking a sigh she gestured him inside and went in to her living room, letting him shut the door behind him. Collapsing down on to her sofa she clicked on the tv and waited for it to load up. Jake sat down calmly next to her and dropped the bag on her lap.

"Cheers. It feels like ages since I had this." Unwrapping the baguette she took a big bite and started chewing, glancing sideways at her crew mate.

"Well, you have been off work for two weeks now. Do you have any idea when you'll be back?" The hint of hope in his voice was hard to miss.

Alexis shook her head, tearing another chunk of baguette off. "Nope," she replied with her mouth full. "Management say they want to wait for the investigation to make progress. They say it may distract me too much to be at work. Sitting around is driving me crazy though."

"Have you sorted out your parent's house yet?"

"Its coming along. I've packed everything away and sorted it. Just got to sell it now and get rid of everything. And before you say it – no, I don't want to live there. I don't want to keep all of their belongings."

Jake dipped his head and started eating his own breakfast. He had been nagging her for the last 2 weeks, saying how she needs to keep some momentos, keep the house in the family. But she couldn't move on with all of those reminders. She wasn't doing it to be heartless, but quite the opposite. She couldn't live in that house, it would feel like her life is frozen in time, constantly reminded of the grief threatening to overwhelm her.

The property prices in London were overpriced and she would financially be better off in a house that's already had its mortgage paid, but she just couldn't bring herself to do it.

Jake had devoured his breakfast and was already getting up to throw the wrapper in the bin.

"Well, you need to get out of this flat. I'm going out tonight with some friends for a few drinks and you're coming. Meet me at The Den for 8. No objections."

Alexis sighed as she crumpled up her own food wrapper. "You better make this worth my time, Jacob."

Jake only shot her a weird look as he walked to the front door, and she couldn't decipher what it meant. The look then quickly vanished to be replaced by a shy smile.

"There will be some people there that I want you meet." With that he opened the door and left.

"Bye then!" Alexis called out as he closed the door, and slumped back against the fluffy pillows of her sofa, cradling the warm cup of tea and browsing through the tv channels for something to watch.

She hadn't been out for a drink in so long the thought of it felt alien to her. Having to get ready – wash and style her hair, put make-up on, find an outfit... it required so much effort. The Den was only a casual bar, dark and dingy in a cool kind of way. Couples chilled out in booths, snuggled up against each other. Groups played pool whilst resting their beers round the edge of the pool table. Friends and dates dotted around on tables and stalls of varying sizes. It was just a welcoming place to hang out and not be bothered by rude drunks like it can be in the bigger bars.

Ever since her parent's death Alexis had felt like a shadow of her former self, almost wasting away to nothing. Maybe it was time to start living again.

But she didn't need to get ready for quite a few hours yet and this sofa was _so_ comfy.

Getting ready actually took longer than Alexis had expected and it was half 8 by the time she left the flat. The bar was 20 minutes away on foot so she decided to walk. Her long blond hair was tied up in a messy ponytail with the hair curled at the bottom and her short side fringe styled out of the hair band. Her chosen septum jewellery was a black ring and matched the multiple other ear and labret piercings she had. She'd had them all done years ago but had to take them out whilst working. Her look was a casual – dark blue skinny jeans with a black top, slightly tight so it showed off her figure, with thick heeled boots and a dark military style jacket. The later October air was colder than she expected and she shivered, but she had walked too far now to go back and get a warmer coat.

Turning the corner she had come to the road The Den was on and could see the sign down the other end of the street – a twinkling neon sign of an illuminated full moon with a black silhouette of a wolf's head thrown back in a howl. Not exactly original but it worked.

As Alexis was walking along the pavement, her heels clicking against the stone, she noticed the street gradually becoming darker. The streetlamps flickered and the very air became still and stale. A fog darker than night itself began to creep around the edges of the street. Was it her vision? She stopped abruptly in the middle of the street and held her breath, not knowing where to look in case she saw another one of her hallucinations.

Not tonight, please.

Several things happened at once. Alexis let out her breath and it turned to mist in the sudden freezing air. A shape appeared at the other end of the street by The Den that looked like an elongated body, thin and deformed and hovering a foot above the ground. The creature flickered, disappearing for only a second and reappearing a few metres closer to her. It's ice blue eyes bore in to hers as it opened its mouth and let out a piercing screech that sounded like its very soul was being tortured. It was coming for her.

Her mind burst in to action and she spun on her heel, desperate to get as far away from this thing as possible. This had to be real this time, how could it not be?! But it was real that time she was scratched by that hand... had she been denying it all this whole time...

 _Get a grip Alex! Run!_

She pumped her legs faster and hurtled round a corner, taking no notice of where she was heading, as long as it was in the opposite direction to The Den. She could still hear the shrieking and electricity crackling in the air as the Horror kept jumping closer. Now she wished she had kept going to the gym in the past few weeks as her lungs started to burn, but she kept pushing herself.

Running across the empty road she turned another corner and had lost sight of it when a pair of hands suddenly grabbed her from the shadows and dragged her in to an alleyway. Gasping in surprise Alexis was thrown roughly against the damp brick wall of the alley. A rough hand clasped around her mouth and as her vision focused again she could only see someone standing before her in a dark hood that obscured their face. The stranger held a finger to their lips as if to say quiet, and they waited.

Alexis could hear the screaming coming closer, cut off whenever it vanished only to resume when the creature reappeared again. It sounded... angry. Even angrier than before. She couldn't describe how, but it made her blood run cold. Turning her head towards the opening of the alley she tried to flatten herself against the wall even further just as it appeared in front of them. This monster looked like it may have been a woman once and seemed tall, at least 6 feet. Her skin was the dead grey colour of the hands she had kept seeing over the past month. As it paused it stopped it's noise to sniff at the air, it's thin wisps of greasy hair dangling limply over its shoulders. Only a rag hung off its body for clothing. It was horrifying.

Not sensing Alexis anymore the thing finally vanished and the air around her suddenly snapped back to normal – it didn't seem so dense and foggy, and it was a little less cold. Now she turned her attention back to the stranger in front of her. Pulling the hand still clasped over her mouth away she gasped in a breath of fresh air and gathered up the courage to speak.

"Who are you?!" She asked stupidly, saying the first thing that popped in to her mind.

The person choked out a laugh and started pacing in front of her, clearly eyeing Alexis up and down.

"Seriously? What a stupid question. I just saved your life, how about a thank you?"

The voice was... female. Alexis blushed as she pushed herself away from the wall and brushed the loose hair from her face. "Thank you," she muttered. "But I would still like to know who you are. After all, you did save my life."

The girl sighed and stopped pacing, resting her hands on her hips. She seemed to be muttering to herself.

"What to do with her... she's just a human, she needs to be cleansed. And yet, she has the sight... might be important somehow. What will Marcus make of this?"

The girl had clearly made her mind up as she slipped out a phone and began texting frantically. Finished, she looked directly at Alexis – who had just been staring in bewilderment - and sighed.

"I'm sorry about this."

Clicking her fingers a blue wisp of smoke rose from the tips of them and Alexis' eyes rolled back. The strange girl managed to catch her as she passed out and laid her gently against her shoulder.

There was a worried look in her as she waited in this alley with an unconscious girl, and wondered if she had done the right thing.


	3. Chapter 3

**Chapter 3**

The white walls were so blindingly bright that as Alexis opened her eyes she immediately squeezed them shut again, groaning at the pain. Lying there she focused on her other senses as she tried to get a grip on what had just happened; she remembered the creature, the darkness, the running... A random girl grabbing her, and then she must've passed out. Probably from the stress, she figured.

There was silence around her and her breathing felt thunderous as it quickened. As she sluggishly moved her legs she felt fabric on top of her. A quilt? Was she on a bed? That definitely felt like a pillow and mattress underneath her. Cautiously forcing her eyes open she sat up on her elbows and glanced around.

It looked like a hospital room. Only, there wasn't any medical equipment that she recognised - just a row of beds with a large machine next to each one. Squinting she was blinking furiously to try and clear the sleep from her mind when the door opened and a man walked in.

He looked about 25 and the first thing she noticed was his messy blond hair, styled casually in a way that made her think he loved himself a little. He was dressed in all black, wearing thick boots, combat trousers and a tight top that drew attention to his muscles – okay, maybe he loved himself a lot.

"Ah, Sleeping Beauty awakens. You were unconscious for a little longer than we expected. I guess Emily packed quite a punch. How are you feeling?" His voice was strong and confident, with a large dose of sarcasm mixed in. He looked directly at her with a slight smirk of amusement on his handsome face.

"Well, I'm feeling confused," Alexis shot back as she swung her legs over the edge of the bed. "Where am I?"

The guy smirked and and shrugged his shoulders playfully. "Emily also said that you ask simple questions. All in good time, blondie. Now, if you would follow me we need to get this thing started. Careful as you stand up, your legs might be a bit weak."

Pushing herself off the bed she had to grab the mattress as she landed on her feet as her knees buckled beneath her, whilst the man just stared. The floor was cold under her bare feet. Where were her shoes?

Gathering up her strength Alexis straightened up and took one tentative step forward, then another.

"Hallelujah, you can walk! What a miracle. Now let's go." Impatience was obvious in his voice as he took off down the corridor, not looking back to see if she followed.

Scrambling after him Alexis had to almost jog to keep up. They didn't talk as they walked and the only sounds were the heavy thumps of his boots and the padding of her feet. The hallway was long and wooden doors were at even paces along the wall. The house was decorated in old-fashioned English style – thickly framed paintings adorned the walls and were mostly portraits or luscious views of the countryside; thick red carpet was laid along every corridor with tall lamps lighting the way. There was no electricity or even candles here, but the lamps seemed powered by a strange white light that Alexis couldn't figure out. Overall the decor had a homely and comfortable feel to it. As they walked she got the feeling that they were in some sort of mansion.

The stranger in front glanced back as he hopped up a flight of stairs two steps at a time, and Alexis was beginning to lag behind. She still felt sluggish and exhausted. When she got to the top of the steps he made an impatient noise and strode off down the hall like he owned the place.

"I actually haven't got all day, you know. I'm a busy man."

This place sure didn't seem busy. What exactly did he do for a living? Eventually, after more twists and turns down corridors that all looked the same they came to a wide oak double door with a strange symbol engraved on it. Pushing the doors open they both strode inside only to be in a room full of people speaking in hushed tones. They all stopped when they entered and stared at Alexis, scrutinizing her.

Alexis stopped dead in her tracks and was about to walk back out when they blond guy grabbed her shoulders, steered her over to a chair and pushed her in to it. She had no choice but to stay, then.

There were about 8 other people in the room, which looked like some sort of library, and they were all seated around a large oval table. Everyone wore the same black outfit like it was some sort of uniform, and all looked like they could kill you in very creative ways.

A young woman with wavy red hair smiled at her from across the table and stood up as if to address everyone. But she looked straight at Alexis.

"I'm glad to see you are awake and looking well." Did she? Alexis was pretty sure she looked a wreck.

"My name is Clary, and the guy that you have already met next to you is Jace. We run the New York Institute."

"We're quite famous. I'm sure she knows who we are Clary." Jace shot Alexis a wink that only made her raise her eyebrows in disbelief at his arrogance.

"Actually, no, I have no idea who you are, _Jace_." Alexis snapped back as she sat up straighter in her chair. It was time to start speaking up for herself. "I don't know anything about some 'New York Institute' either. What even is that?! Last time I checked I was in London. And you can't hold me here against my will so I'm leaving this nightmare."

She started to rise from her chair but Jace placed a hand on her shoulder.

"You mean you have no idea where you are or what's going on?" Clary asked, confusion written all over her face. She glanced around uneasily at the others who seemed just as confused and even concerned.

"And you don't know who I am?" Jace added in a hurt tone. Was this guy serious?

"Jace, stop it. This is more complicated than I first thought." Clary sat back down and leaned back in her chair, deep in thought.

Someone fidgeted further down the table and caught Alexis' eye. The woman cleared her throat and spoke.

"I believe that this girl knows absolutely nothing of the Nephilim or our world. It was clear when I saw her last night. I don't think she knows who she truly is."

The woman looked directly at Alexis with piercing eyes and it took Alexis a moment to notice that her skin was a faint sky blue. She moved to leave again but Jace's hand was still clasped on her shoulder.

"Look, I've had a really tough time lately and I'm going to assume I'm having some sort of psychotic breakdown. So if you would just let me leave, I'll take myself to the nearest hosp-"

"Oh, you can't leave, Alexis. I'm sorry. It's too dangerous for you. I know this is a lot to take in, but you have to trust that we are trying to protect you. You need to know about us - about yourself – and we need to figure out why you are so important." Clary replied. Her voice was soft and reassuring, and she had a genuine look of kindness about her. But this whole situation was freaking Alexis out.

"How do you know my name?"

Clary smiled sadly. "We know more than that. But it's still not enough. You must be tired, you should rest for tonight and we can have a proper talk tomorrow." She looked at Jace who stood up again and nodded.

"I'll show you to your room, this place is like a maze." Striding to the door he opened it and raised his eyebrows at her. "Well come on then."

Alexis glanced at Clary and pursed her lips. She wanted to know more. She didn't want to be herded from room to room and not told anything like a child. Her feelings must have shown on her face because Clary spoke again.

"We will talk tomorrow and I'll tell you everything. I promise."

Alexis sighed and stood up, accepting her fate for tonight. Following Jace he led her up another flight of stairs and to a vacant bedroom.

"Here we go. Nice and comfortable. Bathroom is down the hall and to the right, the last door. You can wander around the house but try not to eavesdrop on any of our super secret meetings. Just don't leave the house. You're kind of our prisoner at the moment. Lucky you, eh?!" Jace gave one last dazzling grin before walking off and leaving her alone.

Sighing, Alexis closed the door and sat tentatively on the bed, her mind whirling, going over all of the events that had happened in thee last 24 hours. Trying to piece it all together and find some clue as to what mess she was in. What is a Nephilim? What do they mean by "our world"? They certainly knew who she was. Lying back on the bed she laid there for the next couple of hours before sleeping finally dragged her under.


	4. Chapter 4

**Chapter 4**

Jace re-entered the library a few minutes later and closed the door behind him. Taking his seat he sat back in the chair, calm and collected as ever.

"So," he began slowly. "There's a new demon about, a new Nephilim that doesn't know what she is, and as usual the Downworld is in chaos. Did I leave anything out?" He looked around expectantly.

Clary still looked worried. "I don't like this. We don't know anything. We are going to have to do our research with this one. That poor girl, this must all be so confusing and scary for her... Maybe I should go up there now..."

Jace only shook his head. "She's exhausted, even if she can't admit it. I think that whatever has been happening to her lately is taking it's toll. Let her rest for now." A small supportive smile from him convinced Clary that he was right.

"So, Emily – did you get any vibes from Alexis whilst she was here?" Clary asked, and everyone at the table turned to her.

"Yes. Kind of. She's very difficult to read. I can usually read everyone's auras – I can see what race they are, what they're feeling. Stuff like that. I can sense the Nephilim in her but it's mixed with something else. Sort of like you and Jace, but magical in a different way. It's hard to describe... but I know for sure that she's not one hundred percent Nephilim."

"Maybe we should ask Magnus, he might have an idea." Alec spoke calmly and quietly, but his voice carried across the room. "Although right now he should be putting the kids to bed..."

"We can ask him tomorrow, it's fine." Clary shook her head and put her head in her hands, making her curls bounce. Jace watched her with the fascination that he always did. "Okay, tomorrow we will begin. We need to find out more about this demon, about who Alexis is and her past. They're all linked. Let's get some rest."

They all stood up from the table, chairs scraping against the carpet, and went their separate ways out of the room until only Jace, Clary and Alec remained. Clary leaned against the table and waited until everyone had gone before turning to the Parabatai pair.

"We need to protect her. I know how it feels being shoved in to this world unwillingly. Scared, alone, powerless. I want her to get used to it as smoothly as possible."

Jace nodded and took hold of her hands, giving them a reassuring squeeze. "I know. We will protect her."

Alec nodded. "I should probably get going. I'll talk to Magnus tonight and see what he thinks. He will probably want to see her for himself at some point."

Giving both of them a hug he waved awkwardly and left, off to find Emily to make a portal for him.

Clary sighed and looked at Jace. "I want to stay here for a while, in London. Help Alexis." She wanted to be like a mentor for her, be there for her and understand her in a way that she didn't get when she was introduced to this world. Jace knew that she was going to say something like this.

"I know. You have a good heart, Clary. I'll stay here for a few more days then head back to New York. The institute just isn't the same without me – everyone knows it."

Clary scoffed, which only made Jace smile wider. Running his fingers lightly along her cheek he kissed her gently at the corner of her lips.

"You need to get some rest too, you know." He murmured.

Taking her hand he led them back to their room.


End file.
